Mark Strong - who plays the villainous Lord Blackwood in the film - had previously, exclusively and rather mysteriously told IGN that "Moriarty's in it... but you don't really see him. I think he's there because if the franchise carries on, there's a possibility that he will appear in a larger guise."

Now however, The Mirror is claiming that studio executives demanded more Moriarty, with Pitt dutifully stepping into the fray to help out his old friend Guy (the two previously collaborated on Snatch).

According to the paper's source, "Brad Pitt is expected to be filming all over London. Cliveden House has been earmarked as a location for Moriarty's house. There will be scenes shot at Royal Victoria Dock, Pontoon Docks, Pinewood and Chatham Docks in Kent."

Until Warner Bros either confirms or denies this, we recommend taking the news with a pinch of salt, but IGN reckons Ritchie could do a lot worse than Brad Pitt for Moriarty. What do you guys think?

UPDATED: Warner Bros. issued a statement today to MTV denying the rumor: "The report in today's London Mirror is completely inaccurate. Brad Pitt is not joining the cast of Sherlock Holmes and we're extremely pleased with the production of the film. As planned, it will be released on Christmas Day, 2009. In order to complete the movie, we've scheduled a few days on set to shoot a couple of additional scenes, obtain pick-up shots, and perfect some of the visual effects elements, all of which is standard filmmaking practice."